DNS SERVER WITH ERROR: "Server Can't Find : SERVFAIL"

I did a basic installation of Debian, which will be used for a mail server "ZIMBRA". I Installed the bind9 and did the configuration of the zones and created the files in the directory / etc / bind.
After the process I typed the following command to test my DNS:

// This is the primary configuration file for the BIND DNS server named.
//
// Please read /usr/share/doc/bind9/README.Debian.gz for information on the
// structure of BIND configuration files in Debian, *BEFORE* you customize
// this configuration file.
//
// If you are just adding zones, please do that in /etc/bind/named.conf.local

// From the release notes:
// Because many of our users are uncomfortable receiving undelegated answers
// from root or top level domains, other than a few for whom that behaviour
// has been trusted and expected for quite some length of time, we have now
// introduced the "root-delegations-only" feature which applies delegation-only
// logic to all top level domains, and to the root domain. An exception list
// should be specified, including "MUSEUM" and "DE", and any other top level
// domains from whom undelegated responses are expected and trusted.
// root-delegation-only exclude { "DE"; "MUSEUM"; };